CTA and Fire Department officials originally said half of an eight-car Red Line train was involved in a derailment Monday afternoon between the Granville and Loyola stations on the Far North Side, but the transit agency later relabeled the incident as a “split-switch issue.”

None of the more than 100 passengers on the southbound train was hurt during the incident, which occurred at 12:45 p.m. Service on the Red Line, which was shut for almost two hours between Howard and Belmont after the incident, was restored well before the evening rush period, officials said.

None of the cars tipped over, although the last car of the train came to rest straddling two sets of tracks, angled away from the rest of the train, just north of the Granville station.

“There was a derailment here,” Mark Nielsen, assistant deputy commissioner of the Chicago Fire Department, had said at the scene. “What the CTA did with four cars that were involved in the derailment, they split. We’ll get these four cars back on track. The remaining four (cars) took all the passengers that were on board to the Loyola stop.”

As the investigation proceeded, however, CTA officials determined that no derailment occurred because wheels never lost contact with rails.

The problem was that a track switch was misaligned, causing the train, which was traveling on southbound track No. 2, to start crossing over to northbound track No. 3, CTA spokeswoman Tammy Chase said.

The operator immediately recognized the problem and stopped the train, Chase said. The operator then walked to the last car of the train and tried to back up the train to get the front car off track No. 3 and off the crossover switch and back onto track No. 2, Chase said.

But the attempted maneuver was halted, leaving the wheels on the front end of the train on the northbound track and the wheels at the rear of the train on the southbound tracks, officials said.

“The train did not derail because (it) never left the track. (But) the wheels were not where they were supposed to be,” Chase said.

Another CTA spokeswoman, Catherine Hosinski, subsequently characterized the incident as a train that took an incorrect route.

The reason that the track switch was incorrectly aligned to move the train from one track to another, instead of continuing straight, was not immediately known and remains under investigation, CTA spokesman Brian Steele said.

He said it was too early to determine whether a mechanical failure or human error caused the problem.

Inspectors found damage to the tracks, Steele said. The rail cars were also inspected, and six of the eight cars were returned to service, he said.